Arc-lamp electrode.



I PATENTED 001. 15, 1907. 0.v P. S'IBINIMBTZ.

ARG'LAMP ELECTRODE. APPLIOATION FILED DBO. 7 1904. RENEWED JULY 20. 1907.

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CHARLES l. STEINMETZ, OF SCHENECTADY, NEW YORK, ASSIG'NOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ARC-LAMP ELECTRODE.

Specification of Letters Patent.

Patented Oct. 15, 1907. 1907. Serial u 384.764.

Application filed December 7, 1904, Seriel No. 235,788- Reue'wed July 20,

To all whom it may concern:

Be it known that I, CHARLES P. STEINMETZ, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Arc-Lamp Electrodes, of which the following is a specification.

During the operation of arc lamps having certain kinds of clectrodesaliquid or fiuid pool formed oflmolten material exists at the end of the lower and generally the negative electrode. This liquid pool is formed on electrodes made of materials the boiling point of which is considerably above the melting point. As an example of such electrodes I may mentionthose made of magnetite or titanium carbid, or mixtures of magnetite and titanium compounds- The are in its passage from an electrode of the general character specified is carried by means ofa bridge of vapor issuing from a point on the negative electrode and has apparently the character- .the are from one granule to another the istics of a high velocity blast. The reaction of this high velocity blast upon the point where it leaves the negative' electrode causes anoticeable depression in the liquid .pool. The arc, however, tends always to pass across the shortest distance between the electrodes and therefore tends to climb up the sides of the depression. In doing so a new spot in the liquid pool is depressed. A continuance of this action results in a more or less rapid motion of the negative spot over the liquid pool and thus causes a trembling or rapid hiiieker of the arc flame.

I have found that if, instead of using a homogeneous mixture for the electrode from which the arc blast issues, I use a mixture consisting of a practically homogeneous body interspersed with a refractory material in granulated form, say in grains of 1/32 to 1/ 16 of an inch diameter, then when the liquid pool is formed these grains of refractorymaterial project above the surface of the pool and serve to center the point of emission of the arc flame or blast. The action continues until the granule is gradually worn below the surface of so on. Except for relatively infrequent transitions of Patentoi the United States, is,

material which melts locally where the are springs therethe pool whereupon the arc jumps to the next grain and arc flame remains absolutely steady. I

In the drawings I have represented an electrode cmbod ying my invention. This electrode may consist of a thin metal tube such as 1 filled with a suitable compound of some finely powdered material as 2, having interpersed therewith granulessuch as 3 of some more refractorm material. The filling for the metal tube can bemade by packing the same into the tube in the form of powder, or by first molding the material into sticks and then inserting the sticks into'the tube. The electrode may of course consist merely of the molded stick. The body of the electrode, such as 2, may consist of powdered magnetite and titanium, while the granules 3 may, for example, consist of chromite. Instead of the granules of chromite I may use granules of titanium oxid.

Whatever the chemical constituents of the electrode material may be it will be understood that the general principle of my invention is to have some constituent of. the electrode in more or less granular form and of a nature which is more refractory than the body of the electrode with which it is interspersed.

What I claim as new, and desire tosecure by Letters '1. An are light electrode consisting of a mixture of a powder with granules ot a more refractory material than the powder.

2. An are light electrode, the'body of which is formed of from, and granules of relatively more refractory material mixed Withsaidhody of material; whereby, when the electrode is in operation, they project above the liquid pool formed by the melted portion of the body of the electrode.

3. An are light electrode formed of a number of inter- 7 spersed constituents, one of which is more refractory than" the rest and remains unfused in the melted pool formed on the electrode during operation whereby it steadies the arc.

In witness whereof I have hereunto set my hand this 6th day of December, 1904,

CHARLES 1? STEINMETZ.

Witnesses BENJAMIN B. HULL, HELEN Ourono. 

